private void RotateLeft()
{
//NEED TO COMPLETE
//rotate left about THIS root
Left = new ExpressionTree <T>(Key, Left, Right.Left);
Key = Right.Key;
Right = Right.Right;
Height = 1 + Math.Max(Right.Height, Left.Height);
}
private void RotateRight()
{
//NEED TO COMPLETE
//rotate right about THIS root
Right = new ExpressionTree <T>(Key, Left.Right, Right);
Key = Left.Key;
Left = Left.Left;
Height = 1 + Math.Max(Right.Height, Left.Height);
}
public virtual string Inorder(ExpressionTree <T> tree)
{
if (tree == NIL)
{
return("");
}
try
{
string data = tree.Key.ToString();
return("(" + Inorder(tree.Left) + " " + data + " " + Inorder(tree.Right) + ")");
}
catch (Exception ex)
{
MessageBox.Show("Error: please reformat your initial expression.");
return("");
}
}
private ExpressionTree <string> TreeConversion(string postfix)
{
Stack <ExpressionTree <string> > s = new Stack <ExpressionTree <string> >();
char[] delims = { ' ' };
string[] pieces = (postfix).Split(delims, StringSplitOptions.RemoveEmptyEntries);
for (int i = 0; i < pieces.Length; i++)
{
if (Regex.IsMatch(pieces[i].ToString(), @"^\d+$")) //if the piece is a number
{
//create a singleton tree and push it onto the stack
ExpressionTreeLeaf <string> single = new ExpressionTreeLeaf <string>(pieces[i].ToString());
s.Push(single);
}
//if the current piece is an operator
else if (Regex.IsMatch(pieces[i].ToString(), "[+-/*]"))
{
//pop the stack twice
if (s.Count() >= 2)
{
ExpressionTree <string> tree1 = s.Pop();
ExpressionTree <string> tree2 = s.Pop();
ExpressionTree <string> newTree = new ExpressionTree <string>(pieces[i].ToString(), tree2, tree1);
s.Push(newTree);
}
else
{
return(emptytree);
}
}
else
{
continue;
//whitespace
}
}
if (s.Count() > 0)
{
return(s.Pop());
}
return(emptytree);
}
private void EvaluateClick(object sender, EventArgs e)
{
string expression = uxInitialExpressionTextBox.Text;
//check if expression is empty or if there's any symbols, letters, or stuff
if (expression == "" || RemoveSpaces(expression) == " ")
{
MessageBox.Show("Error: Please enter something for the initial expression!");
//uxInitialExpressionTextBox.Text = ""; //clear out textbox
return;
}
else if (!IsProperFormat(expression))
{
MessageBox.Show("Error: Please remove letters and unsupported symbols from the initial expression!");
//uxInitialExpressionTextBox.Text = ""; //clear out textbox
return;
}
//reformat with some spaces between operators
expression = AddOperatorSpaces(expression);
//now it's good
string InitialType = uxInitialTypeComboBox.Text;
string postfix;
ExpressionTree <string> tree = new ExpressionTree <string>();
switch (InitialType)
{
case "Infix":
{
postfix = InfixtoPost(expression);
if (postfix == "")
{
MessageBox.Show("Error: Invalid infix expression.");
return;
}
else
{
tree = TreeConversion(postfix);
}
break;
}
case "Prefix":
{
postfix = PretoPost(expression);
if (postfix == "")
{
MessageBox.Show("Error: invalid prefix format.");
return;
}
else
{
tree = TreeConversion(postfix);
}
break;
}
case "Postfix":
{
tree = TreeConversion(expression);
break;
}
default:
MessageBox.Show("Error: please enter a valid choice!");
break;
}
//now we have our expression tree
if (tree == emptytree)
{
MessageBox.Show("Error: tree conversion unable to be completed.");
return;
}
else
{
if (tree.SolveTree() == 0)
{
MessageBox.Show("Error while evaluating");
}
else
{
MessageBox.Show("Answer: " + tree.SolveTree());
}
}
}
private void ConvertExpressionClick(object sender, EventArgs e)
{
/*
* Read in expression
* Convert to postfix
* Build an expression tree
*/
string expression = uxInitialExpressionTextBox.Text;
//check if expression is empty or if there's any symbols, letters, or stuff
if (expression == "" || RemoveSpaces(expression) == " ")
{
MessageBox.Show("Error: Please enter something for the initial expression!");
//uxInitialExpressionTextBox.Text = ""; //clear out textbox
return;
}
else if (!IsProperFormat(expression))
{
MessageBox.Show("Error: Please remove letters and unsupported symbols from the initial expression!");
//uxInitialExpressionTextBox.Text = ""; //clear out textbox
return;
}
//reformat with some spaces between operators
expression = AddOperatorSpaces(expression);
//now it's good
string InitialType = uxInitialTypeComboBox.Text;
string ResultType = uxResultTypeComboBox.Text;
//find the initialtype selected in the combobox
switch (InitialType)
{
case "Infix":
{
string postfix = InfixtoPost(expression);
if (postfix == "")
{
MessageBox.Show("Error: Invalid infix expression.");
return;
}
else
{
switch (ResultType)
{
case "Infix":
{
//update result box to expression
uxResultTextBox.Text = RemoveSpaces(expression);
break;
}
case "Prefix":
{
ExpressionTree <string> t = TreeConversion(postfix); //convert to exp. tree
//do a preorder transversal
if (t == emptytree)
{
MessageBox.Show("Error: tree conversion unable to be completed.");
return;
}
else
{
uxResultTextBox.Text = RemoveSpaces(t.Preorder(t));
}
break;
}
case "Postfix":
{
//convert to postfix, using function
//also remove any extra spaces and replace them with " "
uxResultTextBox.Text = RemoveSpaces(postfix);
break;
}
default:
MessageBox.Show("Error: Invalid Option");
break;
}
}
break;
}
case "Prefix":
{
string postfix = PretoPost(expression); //convert to postfix
if (postfix == "")
{
MessageBox.Show("Error: tree conversion unable to be completed.");
return;
}
else
{
ExpressionTree <string> t = TreeConversion(postfix); //convert to exp. tree
if (t == emptytree)
{
MessageBox.Show("Error: tree conversion unable to be completed.");
return;
}
else
{
switch (ResultType)
{
case "Infix":
//now do inorder transversal
uxResultTextBox.Text = RemoveSpaces(t.Inorder(t));
break;
case "Prefix":
//update result box to expression
uxResultTextBox.Text = RemoveSpaces(expression);
break;
case "Postfix":
//convert from prefix to postfix
uxResultTextBox.Text = RemoveSpaces(postfix);
break;
default:
MessageBox.Show("Error: Invalid Option");
break;
}
}
}
break;
}
case "Postfix":
{
string postfix = expression; //should already be in postfix
ExpressionTree <string> t = TreeConversion(postfix); //convert to exp. tree
if (t == emptytree)
{
MessageBox.Show("Error: tree conversion unable to be completed.");
return;
}
else
{
switch (ResultType)
{
case "Infix":
//now do inorder transversal
uxResultTextBox.Text = RemoveSpaces(t.Inorder(t));
break;
case "Prefix":
//do a preorder transversal
uxResultTextBox.Text = RemoveSpaces(t.Preorder(t));
break;
case "Postfix":
//update result box to expression
uxResultTextBox.Text = RemoveSpaces(expression);
break;
default:
MessageBox.Show("Error: Invalid Option");
break;
}
}
break;
}
default:
MessageBox.Show("Error: Invalid Choice");
break;
}
}
public override string Preorder(ExpressionTree <T> tree)
{
return(_leafdata);
}
